Teletypewriter switchboard



prifi 14, 1936, A, BURGESS ET AL 2,037,1

' TELEIYPEWRITER SWITCHBOARD Filed Dec. 1, 1934 3 Sheets-Sheet l A. A.BURGESS WVENTORSA. 0. KNOWLTON AT T ORA/E k prifi M, 1936. A, A. BURGESSE AL 9 9 TELETYPEWRITER SWITCHBOARD A. A. BURGESS 'NVENTORS AQKNOWLTQATTORNEY Patented Apr. 14, 1936 UNITED STATES PATENT OFFICETELETYPEWRITER swrroneoaan Application December 1, 1934, Serial No.755,584

4 Claims.

This invention relates to an improved teletypewriter exchangeswitchboard designed to enable the size of an operators position to bereadily varied to meet different traffic requirements without requiringmajor alterations of the switchboard apparatus.

A large factor in the cost of a switchboard is the subscriber and tollline multiple. Therefore, it is desirable that the multiple be commontoas many operators as possible in order to cut down the first cost. Intelephone practice, many years of experience have formulated certainwell established principles. However, the teletypewriter art isrelatively new and factors that are easily determined in advance in anestablished art are, in the early stages of this new art, continually ina state of fiux as the service expands and as the development of new andimproved circuits increases operating efiiciency. Because of theuncertainty of the future trend of calling rates and operators loads inthe teletypewriter business, it appears to be sound economic policy todesign teletypewriter exchange switchboards so that they can be readilyadjusted to meet changing trafiic conditions without requiring majoralterations of their apparatus.

Accordingly, it is an object of this invention to provide ateletypewriter exchange switchboard with greater flexibility than hasheretofore been possible.

It is also an object of this invention to enable the operatorsteletypewriters to make efiicient use of the switchboard multiple.

Each switchboard comprises a number of operators positions, the numberbeing determined by the amount of traffic handled during the peak loadand the amount of traffic each operator is capable of handling. Becausethe switchboard multiple is an expensive item, it is desirable, in orderto make eflicient use of it, to place the maximum number of operatorsbefore it by making each operators position as narrow as possible.

The major factor governing the width of the operators positions is thenumber of cords required per operator. The number of cords required peroperator is determined by the average working time together with theaverage holding time which, in turn, depend on traffic conditions in theparticular area and also on the efficiency .of the circuits at thedisposal of the operator. Another factor governing the width of thepositions is the minimum space required by an operator in which to work.Efficiency demands that .the operators be placed on as close centers aspossible, the minimum centers bein determined by the elbow room requiredfor eificient operation. However, in teletypewriter switchboards, thereis an important element which decreases the efficiency of the use of themultiple; namely, the operators teletypewriter. This is approximate- I1y sixteen inches in Width and ten and one half inches in height. Thewidth of a particular operators position as based on the pastswitchboard design, shown in Patent 1,867,333 granted July 12, 1932 .toE. M. Smith where the teletypewriter 19 and the cord circuit keys andplugs are placed at approximately key-shelf height, would be determinedby the number of cords plus sixteen inches.

At the present time, it is thought that each 15 operator will requireabout ten cords. The width of her position will, under the conventionaldesign methods, be at least ten times 27/32 plus sixteen inches or abouttwenty-four and one half inches. Constructional details will increasethis figure to about twenty-seven and one half inches. While the numberof cords per position is now considered to be ten, this a Veryuncertainestimate due to changing trafiic and operating circumstances.

The factors determining the number of cords are: the time necesary tobuild up a connection; and the conversation time. It is, of course,reasonable to hope that the development of the art will reduce theconnection, .or working, time. The conversation time is likely to varyconsiderably in areas, seasons, and with the increased use of thesystem. Therefore it does not appear probable that the number of cordscan be determined with any degree of accuracy for some length of timeyet to come. Consequently, it seems highly desirable that.teletypewriter switchboards should ,be designed to permit greatflexibility as to the number of cords assigned to each operator. At thesame time, effi ciency demands that this flexibility be obtained withouttoo great expense.

I he disadvantages resulting from the use of -teletypewriter.switchboards of the type shown in the above-mentioned patent to E. M.Smith are: that, because the teletypewriter is placed at the same levelas the cords, the width of the operators position is made larger thanthat of the operators position at a telephone switchboard; and itrequires that a definite fixed number of cords be assigned to eachteletypewriter or operator. 7 Consequently, a predetermined fixed numberof cords per operator hasto be provided in the ini ia d s o w t hbqardsated ab ve. thi make fo emqi nc h chan in 1 traffic conditions vary theoptimum number of cords per operator.

The present invention enables an operators teletypewriter to beassociated with any number of cords with little change of apparatus and,at the same time, the width of the operator's position is reduced. Thisis accomplished by locating the cord equipment on an overhangingkeyshelf above the teletypewriters and locating the teletypewriters onindividual tables which can be placed anywhere in front of theswitchboard. Because the teletypewriters are mounted on tables in frontof the switchboard, they may be moved up and down the switchboard to anydesired location in accordance with prevailing traffic conditions.

These and other features of the invention will now be described indetail in connection with the drawings in which:

Fig. 1 is a three-dimensional view of a central office having a smallswitchboard constructed in accordance with this invention and having twooperators teletypewriters arranged in front of it;

Fig. 2 is a semi-cross-sectional side view of the central officeswitchboard shown in Fig. 1 and one of the operators teletypewriters;

Fig. 3 is a cross-sectional view of the key-shelf and part of theswitchboard; and

Fig. 4 illustrates the manner in which the size of an operators positionmay be quickly varied to meet changing trafiic conditions.

The central office, shown in the drawings, has been shown as having onlytwo operators teletypewriters 2-2 mounted upon tables 3-3 and arrangedin front of the teletypewriter switchboard I. This has been done for thesake of simplicity and it is to be understood that it may readily bemade longer and have more teletypewriters arranged in front of it ifdesired. It can be seen in the drawings that the switchboard I has aprojecting, or overhanging, key-shelf 4. This is because the depth ofthe teletypewriters '2 -2 makes it necessary to employ the overhangingkey-shelf 4 in order to enable the operators to sit close enough to thejack-field 24 for efficient operation. Since the tables 3-3 are movable,they may be moved up and down the lengthy of the switchboard as desired.Containers I4-I4 are provided for receiving the printed tape emitted bythe teletypewriters 2-2. j

Each section of the switchboard is provided with position relayequipment 5 which is wired 'to terminal strips (not shown) and tomultiby a conduit I0 and taken from outlets II-I I,

"located beside the jacks 1-1, by means of another fiexible cord I2 andplug I3.

l At intervals along the front of the key-shelf 4, -c'locks I5-I5 areprovided to enable the operatom to time messages as a basis fordetermining ,the amount to be charged. Telephones Iii-I6 .are located atintervals along the top front of the switchboard I. These telephonesI6-I6 are connected to cords I'I inside the switchboard I and held downby weights I 8-I8. The cords I'I-I'I terminate at a connecting block I9.Located near the telephones IB-IG are the visual busy test lamps 20-20and ticket boxes 2I-2I for storing themessage rate tickets 22-22 held by--the ticket spring clips 23-23 on the teletypew'r'iters- 2-2. Lowerdown on the front of the switchboard I are the jacks 25-25 in the jack-Next comes the projecting key-shelf 4 with the plugs 28-28, supervisorylamps 29-29 and keys 30-30. The conventional method of locating theplugs 28-28 is to place the calling plugs all in one row and theanswering plugs in another. However, to conserve multiple space bykeeping its height at a minimum and to reduce the depth of the key-shelf4, this conventional method has been departed from and all the plugs28-28 have been placed in one row, the right plug 28 of a pair being thecalling plug and the left plug 28 being the answering plug.Differentiation between the two types of plugs 28-28 may be obtained byany suitable means, such as by equipping the calling plug with a redplug shell and the answering plug with a black shell.

The plugs 28-28 are connected to cords 3I-3I which, with keys 30-30 arewired to terminal strips (not shown) in the rear of the switchboard. Dueto the overhang key-shelf 4, it is necessary that the cords 3 I-3I berun back into the switchboard I so that the operators teletypewriters I2-2 can be moved up and down directly beneath the projecting key-shelf.To enable the cords 3I-3I to' be pulled out without incurring anyappreciable amount of friction, a sloping top has been provided for thekey-shelf 4. This top slopes at an angle of about from the perpendicularthereby enabling the cords 3I-3I to be slid straight out from inside theswitchboard. This arrangement produces so little friction that the cords3I-3I can be turned over a stainless steel bar 32 instead of thecustomary pulleys. Because of this slight amount of friction, there isrelatively very little wear and tear of the cords 3 I -3I over a longperiod of use.

The cord relay equipment is mounted in units 33-33 equipped withterminal strips (not shown). These units 33-33, which are very similarto conventional relay rack units, are mounted in the rear of theswitchboard immediately below the terminal strips (not shown) providedfor the cords.

Distributing rings (not shown) areprovided above these terminal stripsso that any cord relay equipment 33 may be cross-connected to any cord3I in the key-shelf 4 either in the same or in a different section ofthe switchboard I by crossconnecting between the terminal strips. Thisfacilitates furnishing the minimum number of wired and equipped units33-33, allows additional cords 3 I-3I to be equipped with little effort,and permits quick reassignment of the cords.

To obtain greater flexibility, the cords 3I-3I may be arranged with asplitting key 36-36 between each set of five cords, similar to thestraightforward trunking method to enable the size of an operator'sposition to be quickly varied. The operators position keys 31-31 forrecall release, toll disconnect, and ring-on-answer cord functions aremounted on her teletypewriter table 3 and may be plugged into the jack 1of any position relay equipment. Thus, any number of adjacent pairs ofcord relay equipment 33-33 may be cross-connected to a position relayequipment 5. In addition, each pair of cords 3I-3l is arranged forteamwork with the adjacent position to the left or right, those in theleft half of the position with the position to the left, and those inthe right half of the position with the position to the right. 7

Considerable flexibility is thereby obtained to meet different traificrequirements because any number of cords 3l3l may be assigned to anoperator, cross-connected at the terminal strips in the rear of theswitchboard to the nearest position relay equipment 5, and ateletypewriter 2 and table 3 moved in front of the group of cords 3l3land plugged into the jack 1 and outlet II for that particular position.This enables an operators position to have the number of cords requiredfor the most efiicient operation under prevailing traffic conditionswith very little changes of the switchboard equipment.

This feature of the invention is illustrated in Fig. 4 which showsschematically five sections of a typical teletypewriter switchboard Iwith four operators teletypewriters 22 mounted on tables 33 and arrangedin front of the switchboard I for optimum use of the switchboard I at aparticular time. It can be seen that each section of theswitchboard I ismade up or two panels -35. This particular switchboard l is shown,purely for purposes of illustration, to be a six panel multiple in whichthe equipment in the panels 35-45 is repeated after every sixth panel.Of course, this may be readily varied at will to meet diflerentconditions in different localities. At the left end of the switchboard Iare miscellaneous plugs 28-28 for testing and plugging-up. To the rightof these miscellaneous plugs is operators position A which is shown tohave fourteen pairs of plugs 28--28. Next come ten pairs of cords whichare assigned to operators position B. Operators position C has onlyeight pairs of cords. It will be noticed that there are two idle pairsof cords in position C. This is to separate the operators so as toprovide sufiicient elbow room. Operators position D has eighteen pairsof cords. This method of assigning cords to the operators can, ofcourse. be readily applied to a longer switchboard and can be varied atwill, as described above, to meet difierent traffic requirements. Allthat need be done is to slide the tables 33 up and down the length ofthe switchboard I' to the desired location, assign the cords bycross-connection, and then insert the plugs 9-9 and l3l3 into jacks 11and outlets H-I I.

The above arrangements of apparatus have been shown and described inorder to illustrate the principles and features of operation of thisinvention. It is to be understood that different arrangements employingthe principles and features of operation of this invention may bedesigned. Accordingly, the invention is not to be limited to thearrangements shown in the drawings but is to be restricted only by theclaims appended hereto.

What is claimed is:

1. A teletypewriter central ofiice comprising in combination ateletypewriter exchange switchboard having a projecting key-shelf, and aplurality of operators teletypewriters mounted upon tables locatedunderneath the key-shelf, said tablesbeing adapted to be moved up anddown the length of the switchboard for readily varying the size of anoperators position to meet different traffic requirements withoutrequiring major alterations of its apparatus.

2. A teletypewriter central office comprising in combination ateletypewriter exchange switchboard having a projecting key-shelf, and aplurality of operators teletypewriters mounted upon tables locatedunderneath the key-shelf, said tables being adapted to be moved up anddown the length of the switchboard for quickly varying the size of anoperators position to meet different traffic requirements withoutnecessitating major alterations of its apparatus, said keyshelf havingits plugs all in one row for reducing the depth of the key-shelf toenable the operators to be closer to the jack-field.

3. A teletypewriter central ofiice comprising in combination ateletypewriter exchange switchboard having a projecting key-shelf, aplurality of operators teletypewriters mounted upon tables locatedunderneath the key-shelf, said tables being adapted to be moved up anddown the length of the switchboard for readily varying the size of anoperators position to meet difierent trafiic requirements, saidkey-shelf having a sloping top for enabling the operators to be locatedcloser to the jack-field, and plugs with cords attached thereto locatedon the sloping top of the key-shelf at an angle of about forty-fivedegrees from the perpendicular to allow the cords to pass in a straightline from the front of the key-shelf to the inside of the switchboard tosave that wear and tear of the cords caused by friction generated inpulling them in and out.

4. A teletypewriter central oflice comprising in combination ateletypewriter exchange switchboard having a projecting key-shelf, aplurality of operators teletypewriters mounted upon tables locatedunderneath the key-shelf, said tables being adapted to be moved up anddown the length of the switchboard for readily varying the location ofan operators position in accordance with different trafiic requirements,said key-shelf having cords and plugs, and instrumentalities forenabling the optimum number of cords for a given trafiic condition to beassigned to each operator, said instrumentalities including cord relayequipment located inside the switchboard and adapted to becross-connected to any cord in the key-shelf.

ALFRED A. BURGESS. ALFRED D. KNOWLTON.

